Table 3.
A Possible Scenario for Data Collection and Analysis When LR Development in an Arabidopsis Mutant Is Studied
| Questions to Be Answered and Parameters and Data to Be Collected and Reported | Description |
| 1. Questions to be answered before the beginning of the analysis | (a) What is the primary root growth capacity in 5- to 10-d-old seedlings? If the primary root is longer than 10 mm →go to 2a and 2b (optionally to 2c), if it is 10 mm or shorter →go to 2c. |
| (b) Is the LR formation zone at least 5- to 7-mm long in seedlings 5 to 6 d after germination ? If yes →go to 2a and 2b (optionally to 2c), if no →go to 2c. | |
| (c) Is the average cortical cell length in the one-third of the proximal (shootward) root portion the same as within the one-third of the distal (rootward) root portion? Lengths should be compared in at least five roots, 10 cortical cells in each. If cell length is the same →go to 2d, if cell length is different →go to 2d’ and 2d’’. | |
| (d) Are some LRP stages delayed? →go to 2e. | |
| (e) Is LR emergence altered? →go to 2f. | |
| 2. Parameters to be evaluated | (a) LR branching density →go to 3a. |
| (b) LRP density in the LR formation zone →go to 3d. | |
| (c) Density of all LR initiation events →go to 3a and 3d. | |
| (d) LR initiation index within the primary root →go to 3c and 3d. | |
| (d’) LR initiation index within the LR-formation zone →go to 3c and 3d. | |
| (d’’) LR initiation index within the LR-branching zone →go to 3b and 3d. | |
| (e) Distribution of different LRP developmental stages within the LR formation zone (expressed in percentage of total number) →go 3e. | |
| (f) Percentage of LRP of the total LR initiation events within the LR branching zone →go to 3a. | |
| 3. Data to be collected | (a) Length of the branching zone; number of LR within the branching zone; number of LRP within the branching zone. |
| (b) Cortical cell length within the LR branching zone. | |
| (c) Cortical cell length within the LR formation zone. | |
| (d) Distance from the most rootward LRP to the root tip and the length of the LR formation zone; number of LRP within the LR branching zone (when the primordium protrudes through the epidermis of the parent root it is considered to be an emerged LR). | |
| (e) Number (or proportion) of LRP of each developmental stage found within the LR formation zone. | |
| 4. Variables and conditions to be reported | Plant age at the time of the analysis, growth conditions (light, temperature, and photoperiod), medium composition, plate sealing type, how plates were oriented (vertically, at an angle, etc.), whether shoots were in contact with the agar, how LR or LRP density was evaluated (per total parent root length or per specific root portion), in what root portion developmental stages were evaluated. |
Counting of LRPs is performed on cleared root preparations under a microscope.